A former chief-of-staff of the Iraqi army is fighting a legal battle to prosecute Tony Blair over the Iraq war.
General Abdul Wahed Shannan Al Rabbat alleges Mr Blair, then UK prime minister, committed "the crime of aggression" by invading Iraq in 2003.
The general wants to bring a private prosecution against Mr Blair and two other key ministers at the time - foreign secretary Jack Straw and the attorney general, Lord Goldsmith.
Westminster Magistrates Court refused to issue summonses in November last year on the grounds that the ex-ministers had immunity from legal action, and in any event the current Attorney General, Jeremy Wright QC, would have to give consent.
The general applied to the High Court in London for permission to seek judicial review of the magistrates court decision.
After a half-day hearing, two judges reserved their judgment and said they would give their decision on whether to grant permission at a later date.
The general lives in Muscat, Oman, does not possess a passport and could not be at the hearing on Wednesday.
But Court 4 of the Royal Courts of Justice was filled by citizens from Middle East countries including Iraq and Syria who say they feel they have had to pay the price of the Iraq invasion.
The Attorney General intervened in the case and his legal team urged Lord Thomas of Cwmgiedd, the Lord Chief Justice, sitting with Mr Justice Ouseley, to block the general's legal challenge on the grounds that it was "hopeless" and unarguable because the crime of aggression is not recognised in English law.
The UK was part of the coalition led by the US which invaded Iraq to depose its president Saddam Hussein.
Both US president George W Bush and Mr Blair had accused Hussein of possessing weapons of mass destruction and having links to terrorists.
Michael Mansfield QC, appearing for General Al Rabbat, said the inquiry into the invasion conducted by Sir John Chilcot, which concluded with a report published in July last year, justified the prosecution of Mr Blair.
Mr Mansfield said the main findings were contained in a paragraph early in the 12-volume report and could be summarised as concluding that Hussein did not pose an urgent threat to the interests of the UK, and the intelligence regarding weapons of mass destruction had been presented with "unwarranted certainty".
It also concluded that peaceful alternatives to war had not been exhausted and that the war in Iraq was not necessary.
The report found that the US and UK had undermined the authority of the UN Security Council by invading without its authority.
Mr Mansfield told the court: "Nothing could be more emphatic than this evidence.
"It does not say there was an unlawful war or crime of aggression.
"It doesn't need to because the criteria are arguably all there in that paragraph."
Mr Mansfield disputed the Attorney General's claims that the crime of aggression, which was recognised by customary international law, was not incorporated into domestic law.
He said the UK had assumed jurisdiction over crimes against peace in the Nuremburg Trials of Nazi war criminals at the end of the Second World War in 1945, and it was arguable that the crime of aggression was assimilated at that time through the UK common law.
He argued: "Whilst it is right that the English legal system has a proud and unblemished record of dispensing justice without fear or favour and remains the envy of the world, there may remain the residual or perceived notion that, in resisting the finding that the crime of aggression is part of English law, the courts in this country are somehow reluctant to permit the prosecution of UK nationals and, in particular, its leaders."
James Eadie QC, appearing for the Attorney General, told the judges they must dismiss General Al Rabbat's challenge because it was hopeless.
The court, he said, was bound by a 2006 decision of the House of Lords in the case of "R v Jones" which held that the customary international law crime of aggression was not part of domestic law.
Mr Eadie said it had been deliberately omitted by Parliament when it introduced the International Criminal Court Act 2001, which allows trials in England and Wales of persons accused of genocide, war crimes or crimes against humanity.
Lord Thomas gave Mr Mansfield seven days to make further submissions and said a judgment would be handed down in writing at a later date.
Among civilians from Iraq and other Middle East countries listening in court was a Syrian man who did not want to be named, who said: "This is also our case. We are one of the other countries paying the price for this invasion."